You keep asking about your conception dates and LMP and all of that--- if you a truly worried and concerned then you need to have your doctor explain it all to you to lessen your anxiety!
Hey hun....I wouldn't worry one second about that, especially if your doctor isn't concerned. I am 38 weeks pregnant and when I was about 20 weeks my son was in the 5th % and anything under 10 is considered IUGR, which was scary. However, after all the scary talk, he is now already 8 pounds and I still have 2 weeks to go. No worries and yes, it is possible that your conception date is off. If you had an early ultrasound that is less likely to be the case though. Maybe she's just a petite little girl. You also have to consider how big you and the father were at birth. She should be somewhere in between those two numbers....usually. Good luck!